A filter includes at least two monolithic sorbent segments and a mixing segment between the two monolithic sorbent segments. The monolithic sorbent segments comprise porous sorbent materials that are capable of selectively removing one or more selected gaseous constituents from a gas flow. The filter can be incorporated in a smoking article, such as a cigarette, to remove one or more selected constituents from mainstream smoke. Methods for making the filter and smoking articles including the filter, as well as methods for smoking a cigarette comprising the filter, are also provided.